When I am working on a campaign or an adventure I often start with a technique I stole from the game Microscope

I usually have some idea or a broad high concept I want to use for a campaign. It might not be more than an image or even an emotional experience like foreboding. It could be a themed adventure like “clockwork” but that’s all I’ll have in mind at the start. To move things forward I take a piece of paper and draw a line down the middle. At the top of one column, I write, “Yes.” At the top of the other column, I’ll write “No.”

From there I start making a list in each column. Anything in the “No” column can’t be in the adventure or campaign. Anything in the “Yes” column makes it into the campaign.  You could even make the “Yes” mean “maybe” if you want.  My “Yes” column is more of a “probably” column when it comes to my campaigns. Things that I write down there will probably show up in my campaign at some point but maybe not. As I go along, the feel of the campaign starts to develop.

Things that you might include in your lists: monsters, character classes, specific spells, traps, types of traps, tropes, cliches of all sorts, type of villain, magic items, types of magic items. My “No” list is often much longer than my “Yes” list. As I go along, the themes and feel of the thing I’m working on will take shape and it makes it easier to figure out the next step when I get stuck.  At some point, I stop adding to the two columns. I don’t have a set process for deciding when I’ll go onto creating something based on the list other than needing to get on with the project. I’ll keep the list somewhere I can review it when I need some inspiration or if I feel like I’m getting away from the feel I wanted.

Try it out and see how it works for you.